/**
 * base64加密解密方法
 */

const _keyStr = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789'

const Base64 = function() {
  // private method for UTF-8 encoding
  function _utf8_encode(string) {
    string = string.replace(/\r\n/g, '\n')
    var utftext = ''
    for (var n = 0; n < string.length; n++) {
      var c = string.charCodeAt(n)
      if (c < 128) {
        utftext += String.fromCharCode(c)
      } else if ((c > 127) && (c < 2048)) {
        utftext += String.fromCharCode((c >> 6) | 192)
        utftext += String.fromCharCode((c & 63) | 128)
      } else {
        utftext += String.fromCharCode((c >> 12) | 224)
        utftext += String.fromCharCode(((c >> 6) & 63) | 128)
        utftext += String.fromCharCode((c & 63) | 128)
      }
    }
    return utftext
  }
  // private method for UTF-8 decoding
  function _utf8_decode(utftext) {
    var string = ''
    var i = 0
    var c = 0
    // tips: unused
    // var c1 = 0
    var c2 = 0
    var c3 = 0
    while (i < utftext.length) {
      c = utftext.charCodeAt(i)
      if (c < 128) {
        string += String.fromCharCode(c)
        i++
      } else if ((c > 191) && (c < 224)) {
        c2 = utftext.charCodeAt(i + 1)
        string += String.fromCharCode(((c & 31) << 6) | (c2 & 63))
        i += 2
      } else {
        c2 = utftext.charCodeAt(i + 1)
        c3 = utftext.charCodeAt(i + 2)
        string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63))
        i += 3
      }
    }
    return string
  }
  // public method for encoding
  this.encode = function(input) {
    var output = ''
    var chr1, chr2, chr3, enc1, enc2, enc3, enc4
    var i = 0
    input = _utf8_encode(input)
    while (i < input.length) {
      chr1 = input.charCodeAt(i++)
      chr2 = input.charCodeAt(i++)
      chr3 = input.charCodeAt(i++)
      enc1 = chr1 >> 2
      enc2 = ((chr1 & 3) << 4) | (chr2 >> 4)
      enc3 = ((chr2 & 15) << 2) | (chr3 >> 6)
      enc4 = chr3 & 63
      if (isNaN(chr2)) {
        enc3 = enc4 = 64
      } else if (isNaN(chr3)) {
        enc4 = 64
      }
      output = output +
        _keyStr.charAt(enc1) + _keyStr.charAt(enc2) +
        _keyStr.charAt(enc3) + _keyStr.charAt(enc4)
    }
    return output
  }
  // public method for decoding
  this.decode = function(input) {
    var output = ''
    var chr1, chr2, chr3
    var enc1, enc2, enc3, enc4
    var i = 0
    input = input.replace(/[^A-Za-z0-9\+\/\=]/g, '')
    while (i < input.length) {
      enc1 = _keyStr.indexOf(input.charAt(i++))
      enc2 = _keyStr.indexOf(input.charAt(i++))
      enc3 = _keyStr.indexOf(input.charAt(i++))
      enc4 = _keyStr.indexOf(input.charAt(i++))
      chr1 = (enc1 << 2) | (enc2 >> 4)
      chr2 = ((enc2 & 15) << 4) | (enc3 >> 2)
      chr3 = ((enc3 & 3) << 6) | enc4
      output = output + String.fromCharCode(chr1)
      if (enc3 !== 64) {
        output = output + String.fromCharCode(chr2)
      }
      if (enc4 !== 64) {
        output = output + String.fromCharCode(chr3)
      }
    }
    output = _utf8_decode(output)
    return output
  }
}

const base64 = new Base64()
export default base64

/*
(function(_keyStr) {
  'use strict'
  var _global
  var Base64 = function() {
    // private method for UTF-8 encoding
    function _utf8_encode(string) {
      string = string.replace(/\r\n/g, '\n')
      var utftext = ''
      for (var n = 0; n < string.length; n++) {
        var c = string.charCodeAt(n)
        if (c < 128) {
          utftext += String.fromCharCode(c)
        } else if ((c > 127) && (c < 2048)) {
          utftext += String.fromCharCode((c >> 6) | 192)
          utftext += String.fromCharCode((c & 63) | 128)
        } else {
          utftext += String.fromCharCode((c >> 12) | 224)
          utftext += String.fromCharCode(((c >> 6) & 63) | 128)
          utftext += String.fromCharCode((c & 63) | 128)
        }
      }
      return utftext
    }
    // private method for UTF-8 decoding
    function _utf8_decode(utftext) {
      var string = ''
      var i = 0
      var c = 0
      // tips: unused
      // var c1 = 0
      var c2 = 0
      var c3 = 0
      while (i < utftext.length) {
        c = utftext.charCodeAt(i)
        if (c < 128) {
          string += String.fromCharCode(c)
          i++
        } else if ((c > 191) && (c < 224)) {
          c2 = utftext.charCodeAt(i + 1)
          string += String.fromCharCode(((c & 31) << 6) | (c2 & 63))
          i += 2
        } else {
          c2 = utftext.charCodeAt(i + 1)
          c3 = utftext.charCodeAt(i + 2)
          string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63))
          i += 3
        }
      }
      return string
    }
    // public method for encoding
    this.encode = function(input) {
      var output = ''
      var chr1, chr2, chr3, enc1, enc2, enc3, enc4
      var i = 0
      input = _utf8_encode(input)
      while (i < input.length) {
        chr1 = input.charCodeAt(i++)
        chr2 = input.charCodeAt(i++)
        chr3 = input.charCodeAt(i++)
        enc1 = chr1 >> 2
        enc2 = ((chr1 & 3) << 4) | (chr2 >> 4)
        enc3 = ((chr2 & 15) << 2) | (chr3 >> 6)
        enc4 = chr3 & 63
        if (isNaN(chr2)) {
          enc3 = enc4 = 64
        } else if (isNaN(chr3)) {
          enc4 = 64
        }
        output = output +
            _keyStr.charAt(enc1) + _keyStr.charAt(enc2) +
            _keyStr.charAt(enc3) + _keyStr.charAt(enc4)
      }
      return output
    }
    // public method for decoding
    this.decode = function(input) {
      var output = ''
      var chr1, chr2, chr3
      var enc1, enc2, enc3, enc4
      var i = 0
      input = input.replace(/[^A-Za-z0-9\+\/\=]/g, '')
      while (i < input.length) {
        enc1 = _keyStr.indexOf(input.charAt(i++))
        enc2 = _keyStr.indexOf(input.charAt(i++))
        enc3 = _keyStr.indexOf(input.charAt(i++))
        enc4 = _keyStr.indexOf(input.charAt(i++))
        chr1 = (enc1 << 2) | (enc2 >> 4)
        chr2 = ((enc2 & 15) << 4) | (enc3 >> 2)
        chr3 = ((enc3 & 3) << 6) | enc4
        output = output + String.fromCharCode(chr1)
        if (enc3 !== 64) {
          output = output + String.fromCharCode(chr2)
        }
        if (enc4 !== 64) {
          output = output + String.fromCharCode(chr3)
        }
      }
      output = _utf8_decode(output)
      return output
    }
  }

  var base64 = new Base64()

  if (typeof module !== 'undefined' && module.exports) {
    module.exports = base64
  } else if (typeof define === 'function' && define.amd) {
    define(function() {
      return base64
    })
  } else {
    _global = (function() {
      return this || (0, eval)('this')
    }())
    !('base64' in _global) && (_global.base64 = base64)
  }
}('ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/='))
*/
